1. Field of the Invention
The present invention relates, generally, to methods of manufacturing colloidal crystals using a confined convective assembly, more particularly, to a method for manufacturing two-dimensional and/or three dimensional colloidal crystals on a substrate by infusing colloidal suspension between two substrates and self-assembling colloidal particles by capillary action.
The method of manufacturing colloidal crystals according to the present invention comprises: infusing colloidal suspension in a fine space between two substrates; removing a solvent in the colloidal suspension and moving one side of the substrate to form a meniscus in the fine space between two substrates; and self-assembling colloidal particles by the capillary action generated due to the removal of the solvent of the colloidal suspension in the meniscus to form a colloidal crystal on a substrate.
2. Description of the Related Art
There are various methods to manufacture colloidal crystals such as a spin coating method (R. P. van Duyne, et al., J. Phys. Chem. B. 105, 5599(2001)), LB (Langmuir-Blodgett) (B. van Duffel, et al., J. Mater. Chem. 11. 3333 (2001)), a gravitational sedimentation (H. Miguez, et al., Adv. Mater. 10, 480 (1998)), a convective assembly (K. Nagayama et al., Langmuir 12, 1303 (1996) & P. Jiang et al. Chem. Mater. 11, 2132 (1999)) and an electrophoretic deposition (A. L. Rogach, et al., Chem. Mater. 12, 2721 (2000)).
The spin coating method, which is a widely known two-dimensional colloid crystal manufacturing method, uses a phenomenon that colloidal suspension is placed on a substrate and colloidal particles are self-assembled by a centrifugal force while water is evaporated at the time of spin coating. This method is economical in that a relatively small amount of colloid suspension is used. However, this method is disadvantageous in that it is easily used to silica nano particles with a relatively large concentration and cannot make a uniform two-dimensional colloid crystal on a large area.
LB (Langmuir-Blodgett) method uses a method in which a LB film of a solutizer including colloidal particles is made in an interface between water and air and then the colloidal particles are self-assembled when the solutizer is evaporated. In this method, a two-dimensional colloid crystal can be produced on a relatively large area, but the colloidal particle surface must be chemically modified and the colloidal crystal formed at the interface between water and the air must be moved into a substrate, again.
A gravitational sedimentation, the first known crystal manufacturing method, uses a method in which a solution where high molecular particles and silica nanoparticles are dispersed lasts for a long time and then the particles are precipitated by gravity and self-assembled. The gravitational sedimentation is known as a relatively easy method but disadvantageous in that it requires a long time to manufacture the colloidal crystals and a flawless uniform colloidal crystal can not be made on a large area.
A convective assembly method uses a method in which a solution friendly substrate is vertically placed in a solution where high molecule and silica colloidal particles are dispersed and the solution is distorted on the substrate surface by an interfacial tension and then the colloidal particles are arranged on the distorted surface to form crystals on a substrate when a solvent is completely evaporated. This method is advantageous in that a uniform three-dimensional colloidal crystal is obtained on a relatively large area but disadvantageous in that only limited sizes of the particles can be used and a relatively long time is required.
In addition, an electrophoretic deposition for manufacturing a colloid crystal on an electrode using electric fields in which surface charged nano particle is placed has been suggested. This method is advantageous in that colloidal crystals can be stacked for a short time but is inappropriate for manufacturing flawless colloidal crystals.